Have a look at land and sea http://www.land-and-sea.com/eddy-current-d...dynamometer.htm , how hard would it be to make a small eddy current retarder ?
http://www.cs.wright.edu/people/faculty/sthomas/stand2.html , just remember speed is a issue with heavy moving objects , so on a direct coupled eddy current dyno one is limited to the speed one can turn the retarder.
Have to look into high speed bearings , some form of lubrication system and possible a cooling system of some sort ( Heat exchange).
Most retarder rotors are cast units ?
have a look at the small units land&sea make , they also have a dyno forum you might want to join.
Electronics to control the dyno is the major obstacles one has to over come amongst many others
will keep a close eye on this thread as I'm always interested i the workings of any dynamometer whether its electrical , hydraulic and mechanical.
cheers
